<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%--增加了session域对象：--%>${sessionScope.online=100}
<%--修改session域对象：--%>${sessionScope.online=200}
<%--删除session域对象：--%>${pageContext.session.removeAttribute("online")}
</body>
</html>
